Method for manufacturing liquid crystal display panels

ABSTRACT

A method for manufacturing an LCD panel comprises: (a) continuously feeding an LC cell comprising first and second substrates, the first substrate being relatively less susceptible to electrostatic decay than the second substrate, (b) laminating a first polarizing plate to the first substrate of the LC cell while avoiding direct contact between the first laminating member and the first substrate; (c) laminating a second polarizing plate to the second substrate with the first substrate being in contact with a second laminating member through the first polarizing plate laminated to the first substrate in the step (b) while avoiding direct contact between the second laminating member and the first substrate, thereby obtaining an LCD panel, and (d) conducting an inspection of the LCD panel without applying voltage, wherein steps (a), (b), (c) and (d) are performed sequentially in a single continuous feed line.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.13/154,023 filed Jun. 6, 2011, which is based upon and claims thebenefit of priority from the prior Japanese Patent Application Nos.2010-143718 and 2010-257424, filed on Jun. 24, 2010 and Nov. 18, 2010,respectively, the entire contents of which being incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates a system and a method for continuouslymanufacturing liquid crystal display panels. More specifically, theinvention relates to a system and a method for manufacturing liquidcrystal display panels by a process that includes sequentially bondingfirst and second polarizing plates, which are drawn and supplied fromfirst and second polarizing plate rolls, respectively, to both surfacesof a liquid crystal cell to form a liquid crystal display panel; andoptically inspecting the liquid crystal display panel.

2. Background Art

A system for continuously manufacturing liquid crystal display panels isdisclosed, in which first and second polarizing plates, which are drawnand supplied from first and second polarizing plate rolls, respectively,are sequentially bonded to both surfaces of a liquid crystal cell toform a liquid crystal display panel (Japanese Patent ApplicationLaid-Open (JP-A) No. 2005-37417). An apparatus for inspecting liquidcrystal display panels is also disclosed, in which light is irradiatedto one side of a liquid crystal display panel, and light transmittedthrough the liquid crystal display panel is imaged at the other side ofthe liquid crystal display panel (JP-A No. 2007-256106). Prior artdocument: Japanese Patent Application Laid-Open (JP-A) No. 2005-37417and Japanese Patent Application Laid-Open (JP-A) No. 2007-256106.

In view of continuous production of high-quality liquid crystal displaypanels, it is advantageous that bonding means and inspection meansplaced in a series of feed lines (in a continuously line) for feeding aliquid crystal cell and a liquid crystal display panel are used in aprocess including bonding polarizing plates to both surfaces of a liquidcrystal cell and then quickly performing optical inspection of theliquid crystal display panel. This is because when the process isperformed in the continuous line with the bonding speed and theinspection speed set equal to each other (or with the inspection speedset higher than the bonding speed), the liquid crystal display panel isprevented from waiting for a long time for the inspection after thebonding process, so that high-quality liquid crystal display panels canbe continuously produced at high speed.

According to findings by the inventors, when a bonding process and aninspection process are performed at high speed in a series of feed lines(in a continuous line) for feeding a liquid crystal cell and a liquidcrystal display panel, non-defective products with no quality problemare sometimes misjudged to be defective in the inspection process. Ithas been found that as a result of re-inspection of such liquid crystaldisplay panels determined to be defective, they are determined to benon-defective. This is considered to be because during the bonding ofthe polarizing plate, the liquid crystal cell is electrostaticallycharged so that the alignment of the liquid crystal molecules arechanged, and due to such an effect, the product, which has been oncedetermined to be defective in the inspection process performed in thecontinuous line, regains the aligned state of the liquid crystalmolecules after a lapse of time, and is determined to be non-defectivewhen re-inspected in such a state.

This problem is a new problem with high-speed continuous production ofliquid crystal display panels, which is caused by a process in which abonding process with bonding means and an inspection process withinspection means are performed at high speed in a series of feed lines(in a continuous line) for feeding a liquid crystal cell and a liquidcrystal display panel.

SUMMARY OF THE INVENTION

The invention has been made under the circumstances described above, andan object of the invention is to provide a system and a method forcontinuously manufacturing a liquid crystal display panel, which havehigh productivity and can inspect products for proper quality even whena bonding step and an optical inspection step are performed at highspeed in serried feed lines (in a continuous line) for feeding a liquidcrystal cell and a liquid crystal display panel.

As a result of investigations to solve the problems, the inventiondescribed below has been accomplished.

The invention is directed to a system for continuously manufacturing aninspected liquid crystal display panel, includes:

a liquid crystal cell supply means that supplies a liquid crystal cellhaving a first substrate and a second substrate;

a first polarizing plate supply means that supplies a first polarizingplate from a first polarizing plate roll;

a first polarizing plate bonding means that bonds the first polarizingplate to the first substrate;

a second polarizing plate supply means that supplies a second polarizingplate from a second polarizing plate roll;

a second polarizing plate bonding means that bonds the second polarizingplate to the second substrate to form a liquid crystal display panelafter laminating the first polarizing plate to the first substrate; and

an inspection means that optically inspects the liquid crystal displaypanel without applying voltage to the liquid crystal panel,

wherein the first substrate is less susceptible to electrostatic decayin the liquid crystal cell than the second substrate.

In the invention, the first polarizing plate bonding means, the secondpolarizing plate bonding means and the inspection means are placed in acontinuous feed line for feeing the liquid crystal cell and the liquidcrystal display panel.

Therefore, the order of bonding the polarizing plates is such that thepolarizing plate is first bonded to the first substrate of the liquidcrystal cell, “which is relatively less susceptible to electrostaticdecay,” and then the polarizing plate is bonded to the second substrateof the liquid crystal cell, “which is relatively more susceptible toelectrostatic decay”. In this case, even when the liquid crystal cell iselectrostatically charged during the bonding of the polarizing plate,the electrostatic charge on the liquid crystal cell can be quicklyattenuated, so that the resulting liquid crystal display panel can bequickly and optically inspected for proper quality (by non-lightinginspection). After the bonding of the polarizing plates, therefore, theliquid crystal display panel can be prevented for waiting for a longtime until the electrostatic charge on the liquid crystal cell isattenuated, or there is no need to apply a voltage to the liquid crystalcell (more specifically, the liquid crystal layer) for removal of theelectrostatic charge on the liquid crystal cell, so that non-lightinginspection of the liquid crystal display panel can be quickly performedfor proper quality. In addition, non-lighting inspection of the liquidcrystal display panel does not need to apply a voltage to the liquidcrystal cell during the inspection, in contrast to a lighting inspectionin which a voltage is applied to the liquid crystal cell, and thereforeallows high-speed inspection. Therefore, the inspection of the liquidcrystal display panel can be performed at a speed equal to or higherthan the polarizing plate-bonding speed, in a series of feed lines (in acontinuous line) for feeing the liquid crystal cell and the liquidcrystal display panel. As a result, the polarizing plate-bonding speedand the liquid crystal display panel-inspection speed, and thus the linespeed itself can be increased in a series of feed lines (in a continuousline) for feeding the liquid crystal cell and the liquid crystal displaypanel (according to the invention, the electrostatic charge on theliquid crystal cell can be quickly attenuated after the bonding of thepolarizing plates, so that the non-lighting inspection of the productscan be performed for proper quality, even when the line speed isincreased so that the time period between the bonding of the polarizingplate and the non-lighting inspection can be reduced. According to theinvention, therefore, liquid crystal display panels can be continuouslymanufactured at high speed in a series of feed lines (in a continuousline) for feeding the liquid crystal cell and the liquid crystal displaypanel.

Examples of the polarizing plate include (1) a roll of a belt-shapedfilm including a belt-shaped carrier film and a belt-shaped polarizingplate formed on the belt-shaped carrier film; and (2) a roll of abelt-shaped film including a belt-shaped carrier film and polarizingplates (polarizing plate pieces) formed on the belt-shaped carrier film(a so-called scored polarizing plate roll). In the case of (1), thesystem of the invention for continuously manufacturing a liquid crystaldisplay panel has cutting means that cut the belt-shaped polarizingplates at predetermined intervals to form polarizing plates (polarizingplate pieces).

The term “continuous line” means a line in which a liquid crystal cellis continuously fed to bonding of polarizing plates (bonding of a firstpolarizing plate and bonding of a second polarizing plate), an opticalinspection (optical inspection of the liquid crystal display panel), andso on.

In an embodiment of the invention, the first polarizing plate bondingmeans bonds the first polarizing plate to the first substrate of theliquid crystal cell, while it feeds the liquid crystal cell from afeed-in side to a feed-out side along the feed line,

the second polarizing plate bonding means bonds the second polarizingplate to the second substrate of the liquid crystal cell, while it feedsthe liquid crystal cell from a feed-in side to a feed-out side along thefeed line, and

the inspection means inspects, in a line mode, the liquid crystaldisplay panel formed by the first polarizing plate bonding means and thesecond polarizing plate bonding means, while the liquid crystal displaypanel is fed from the feed-in side to the feed-out side along the feedline.

According to this feature, the electrostatic charge on the panel, whichis produce during the bonding of the polarizing plates, can be quicklyattenuated, and therefore, when a line inspection is used, the tact timecan be reduced with no trouble (when a line inspection is used, thepanel can be inspected for proper quality, even when the liquid crystalcell and liquid crystal display panel-feed speed is further increased sothat the time period between the bonding of the polarizing plate and theinspection of the panel is further reduced). As a result, high-speedcontinuous productivity of high-quality liquid crystal display panelscan be particularly increased. For example, the line-mode inspection ofthe liquid crystal display panel being fed can be achieved using lightirradiation means for irradiating light to the liquid crystal displaypanel and a plurality of imaging means for imaging the liquid crystaldisplay panel irradiated with light, which are arranged in a linepattern (linearly) along a direction perpendicular to the feed directionof the liquid crystal display panel. In this configuration, the feeddirection of the liquid crystal cell during the bonding of the firstpolarizing plate and the bonding of the second polarizing plate, and thefeed direction of the liquid crystal display panel during the lineinspection may be parallel to one another, reverse to one another, orcrossing or perpendicular to one another, as long as the liquid crystalcell and the liquid crystal display panel are fed in a direction fromthe feed-in side (the side where the liquid crystal cell is fed in) tothe feed-out side (the side where the liquid crystal display panel isfed out) along the feed line.

In an embodiment of the invention, the inspection means includes:transmitted light inspection means has light irradiation means that isplaced on one side of the feed line and irradiates light to one side ofthe liquid crystal display panel; and imaging means that is placed onanother side of the feed line and images the liquid crystal displaypanel irradiated with the light irradiation means.

According to this feature, light transmitted through the liquid crystaldisplay panel is imaged, so that foreign bodies on the surface, surfacescratches, and foreign bodies between the liquid crystal cell and thepolarizing plate can be detected as bright spots. According to theinvention, the inspection can be performed after the electrostaticcharge on the liquid crystal cell is attenuated, and therefore, theinspection can be performed for proper quality. Besides the transmittedlight inspection means, the inspection means may further includereflected light inspection means that irradiates light to one side ofthe liquid crystal display panel from an oblique direction and receivesreflected light from the one side of the liquid crystal display panel tooptically inspect the liquid crystal display panel. This makes itpossible to more reliably detect foreign bodies interposed between theliquid crystal cell and the polarizing plate without lighting the liquidcrystal cell itself.

In an embodiment of the invention, the first polarizing plate bondingmeans includes: a pair of first bonding rollers between which the liquidcrystal cell and the first polarizing plate are caught so that the firstpolarizing plate is bonded to the first substrate of the liquid crystalcell, and

the second polarizing plate bonding means includes: a pair of secondbonding rollers between which the liquid crystal cell with the firstpolarizing plate bonded thereto and the second polarizing plate arecaught so that the second polarizing plate is bonded to the secondsubstrate of the liquid crystal cell.

According to this feature, the polarizing plates can be bonded to bothsides of the liquid crystal cell at higher speed in a continuous manner,and the electrostatic charge on the liquid crystal cell can be quicklyattenuated to a level where the inspection is not interfered with, evenwhen the liquid crystal cell is electrostatically charged by thefriction between the bonding rollers, which makes the inventionparticularly effective. It will be understood that one of the rollersmay be the same as or different from the other.

The invention is directed to a method for continuously manufacturing aninspected liquid crystal display panel, includes:

a liquid crystal cell feeding step including feeding a liquid crystalcell having a first substrate and a second substrate;

a first polarizing plate providing step including providing a firstpolarizing plate from a first polarizing plate roll;

a first polarizing plate laminating step including laminating the firstpolarizing plate to the first substrate;

a second polarizing plate providing step including providing a secondpolarizing plate from a second polarizing plate roll;

a second polarizing plate laminating step including laminating thesecond polarizing plate to the second substrate to obtain a liquidcrystal display panel after laminating the first polarizing plate to thefirst substrate; and

an inspecting step including optically inspecting the liquid crystaldisplay panel without applying voltage to the liquid crystal panel,

wherein the first substrate is less susceptible to electrostatic decayin the liquid crystal cell than the second substrate.

In the invention, the first polarizing plate laminating step, the secondpolarizing plate laminating step and the inspecting step are performedin a continuous feed line for feeing the liquid crystal cell and theliquid crystal display panel.

Therefore, the order of bonding the polarizing plates is such that thepolarizing plate is first bonded to the first substrate of the liquidcrystal cell, “which is relatively less susceptible to electrostaticdecay,” and then the polarizing plate is bonded to the second substrateof the liquid crystal cell, “which is relatively more susceptible toelectrostatic decay”. In this case, even when the liquid crystal cell iselectrostatically charged during the bonding of the polarizing plate,the electrostatic charge on the liquid crystal cell can be quicklyattenuated, so that the resulting liquid crystal display panel can bequickly and optically inspected for proper quality (by non-lightinginspection). After the bonding of the polarizing plates, therefore, theliquid crystal display panel can be prevented for waiting for a longtime until the electrostatic charge on the liquid crystal cell isattenuated, or there is no need to apply a voltage to the liquid crystalcell (more specifically, the liquid crystal layer) for removal of theelectrostatic charge on the liquid crystal cell, so that non-lightinginspection of the liquid crystal display panel can be quickly performedfor proper quality. In addition, non-lighting inspection of the liquidcrystal display panel does not need to apply a voltage to the liquidcrystal cell during the inspection, in contrast to a lighting inspectionin which a voltage is applied to the liquid crystal cell, and thereforeallows high-speed inspection. Therefore, the inspection of the liquidcrystal display panel can be performed at a speed equal to or higherthan the polarizing plate-bonding speed, in a series of feed lines (in acontinuous line) for feeing the liquid crystal cell and the liquidcrystal display panel. As a result, the polarizing plate-bonding speedand the liquid crystal display panel-inspection speed, and thus the linespeed itself can be increased in a series of feed lines (in a continuousline) for feeding the liquid crystal cell and the liquid crystal displaypanel (according to the invention, the electrostatic charge on theliquid crystal cell can be quickly attenuated after the bonding of thepolarizing plates, so that the non-lighting inspection of the productscan be performed for proper quality, even when the line speed isincreased so that the time period between the bonding of the polarizingplate and the non-lighting inspection can be reduced. According to theinvention, therefore, liquid crystal display panels can be continuouslymanufactured at high speed in a series of feed lines (in a continuousline) for feeding the liquid crystal cell and the liquid crystal displaypanel.

In an embodiment of the invention, the first polarizing plate laminatingstep includes bonding the first polarizing plate to the first substrateof the liquid crystal cell while feeding the liquid crystal cell from afeed-in side to a feed-out side along the feed line,

the second polarizing plate laminating step includes bonding the secondpolarizing plate to the second substrate of the liquid crystal cellwhile feeding the liquid crystal cell from a feed-in side to a feed-outside along the feed line, and

the inspection step includes inspecting, in a line mode, the liquidcrystal display panel formed by the first polarizing plate laminatingstep and the second polarizing plate laminating step, while feeding theliquid crystal display panel from the feed-in side to the feed-out sidealong the feed line.

According to this feature, the electrostatic charge on the panel, whichis produce during the bonding of the polarizing plates, can be quicklyattenuated, and therefore, when a line inspection is used, the tact timecan be reduced with no trouble (when a line inspection is used, thepanel can be inspected for proper quality, even when the liquid crystalcell and liquid crystal display panel-feed speed is further increased sothat the time period between the bonding of the polarizing plate and theinspection of the panel is further reduced). As a result, high-speedcontinuous productivity of high-quality liquid crystal display panelscan be particularly increased.

In an embodiment of the invention, the inspection steps includes: atransmitted light inspection step comprising irradiating light to oneside of the liquid crystal display panel and receiving, at another sideof the liquid crystal display panel, light transmitted through theliquid crystal display panel to inspect the liquid crystal displaypanel.

Besides the transmitted light inspection step, the inspection step mayfurther include a reflective light inspection step which includesirradiating light to one side of the liquid crystal display panel froman oblique direction and receiving reflected light from the one side ofthe liquid crystal display panel to optically inspect the liquid crystaldisplay panel.

In an embodiment of the invention, the first polarizing plate laminatingstep includes catching, between a pair of first bonding rollers, theliquid crystal cell and the first polarizing plate to bond the firstpolarizing plate to the first substrate of the liquid crystal cell, and

the second polarizing plate laminating step includes catching, between apair of second rollers, the liquid crystal cell with the firstpolarizing plate bonded thereto and the second polarizing plate to bondthe second polarizing plate to the second substrate of the liquidcrystal cell.

In the system and method of the invention for continuously manufacturinga liquid crystal display panel, the first polarizing plate preferablyhas an electrically-conductive layer. The electrically-conductive layerpreferably has a surface resistance of 1.0×10¹² Ω/square or less. Whenan electrically-conductive layer is provided in the first polarizingplate, the first substrate (liquid crystal cell) can be inhibited frombeing electrostatically charged during the bonding of the first and thesecond polarizing plates, so that any electrostatic charge on the liquidcrystal cell can be more quickly attenuated. In the system and method ofthe invention for continuously manufacturing a liquid crystal displaypanel, the second polarizing plate also preferably has anelectrically-conductive layer. The electrically-conductive layer alsopreferably has a surface resistance of 1.0×10¹² Ω/square or less. Whenan electrically-conductive layer is provided in the second polarizingplate, the second substrate (liquid crystal cell) can be inhibited frombeing electrostatically charged during the bonding of the secondpolarizing plate, so that any electrostatic charge on the liquid crystalcell can be more quickly attenuated.

The liquid crystal display panel includes the liquid crystal cell and atleast the first and the second polarizing plates bonded to both surfacesof the liquid crystal cell, in which a driving circuit is incorporatedas needed. The liquid crystal cell to be used may be of any type such asa vertical alignment (VA) type, an in-plane switching (IPS) type, atwisted nematic (TN) type, or a super twisted nematic (STN) type.

For example, the polarizing plate generally includes a polarizer (about10 to 30 μm in thickness) and a polarizer-protecting film or films(about 20 to 80 μm in thickness) formed on one or both sides of thepolarizer with an adhesive or a pressure-sensitive adhesive interposedtherebetween. The polarizing plate may include an additional film suchas a retardation film (20 to 80 μm in thickness), a viewing anglecompensation film, a brightness enhancement film, or a surfaceprotecting film (about 20 to 50 μm in thickness). These films may alsobe stacked through an adhesive or a pressure-sensitive adhesive. Thepolarizing plate generally includes a pressure-sensitive adhesive layerfor bonding the polarizing plate to a liquid crystal cell. Apressure-sensitive adhesive such as an acrylic pressure-sensitiveadhesive or a silicone pressure-sensitive adhesive may be used to formthe pressure-sensitive adhesive layer. The pressure-sensitive adhesivelayer typically has a thickness of 10 to 40 μm. In general, a(belt-shaped) carrier film (also called “release film”) is attached tothe pressure-sensitive adhesive layer so that the surface of thepressure-sensitive adhesive layer can be protected until the polarizingplate is bonded to a liquid crystal cell. The polarizing plate typicallyhas a thickness in the range of 50 μm to 400 μm.

A known conventional film such as a plastic film (for example, apolyethylene terephthalate film) may be used as the (belt-shaped)carrier film (generally 20 to 50 μm in thickness). If necessary, anappropriate film coated with an appropriate release agent such as asilicone release agent, a long-chain alkyl release agent, a fluoriderelease agent, or molybdenum sulfide may also be used according toconventional techniques.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a liquid crystal displaypanel in embodiment 1;

FIG. 2 is a schematic diagram showing an example of the system accordingto embodiment 1 for continuously manufacturing a liquid crystal displaypanel;

FIG. 3 is a schematic cross-sectional view of a liquid crystal displaypanel in embodiment 2;

FIG. 4 is a graph showing the result of the measurement of verticalalignment (VA)-type CF and TFT substrates for a tendency to beelectrostatically charged;

FIG. 5 is a graph showing the result of the measurement of in-planeswitching (IPS)-type CF and TFT substrates for a tendency to beelectrostatically charged;

FIG. 6A is a diagram for illustrating a line inspection;

FIG. 6B is a diagram showing the process flow of the line inspection;

FIG. 7A is a diagram for illustrating an area inspection; and

FIG. 7B is a diagram showing the process flow of the area inspection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

FIG. 1 shows a schematic cross-sectional view of a liquid crystaldisplay panel Y. The liquid crystal display panel Y includes arectangular liquid crystal cell 4 including a liquid crystal layer 43placed between a pair of first and second substrates 41 and 42; a firstpolarizing plate 10 placed on the first substrate 41 side of the liquidcrystal cell 4; and a second polarizing plate 20 placed on the secondsubstrate 42 side of the liquid crystal cell 4.

Liquid Crystal Cell

In this embodiment, a vertical alignment-type (hereinafter referred toas “VA-type”) liquid crystal cell is used as the liquid crystal cell 4.The VA-type liquid crystal cell 4 is described below.

The first substrate 41 (hereinafter also referred to as the backsidesubstrate) placed on the backside (backlight side) of the liquid crystalcell 4 includes a transparent substrate 411 of glass, plastic or thelike; a circuit part that is provided on the transparent substrate 411and includes a plurality of gate wirings and a plurality of sourcewirings arranged perpendicular to the gate wirings and provided on thegate wirings with an insulating film interposed therebetween; thin filmtransistors (TFT) 412 provided as a plurality of switching elements atthe intersections of the gate wirings and the source wirings; aninterlayer insulating film 413 provided on the switching elements (thinfilm transistors); a plurality of transparent electrodes (pixelelectrodes) 414 provided on the interlayer insulating film 413 andconnected to the switching elements (thin film transistors 412),respectively, through contact holes formed in the interlayer insulatingfilm 413; and an alignment film 415 provided on the transparentelectrodes (pixel electrodes) 414.

The thin film transistors 412 each include a gate electrode, asemiconductor layer opposed to the gate electrode with a gate insulatingfilm interposed therebetween, and source and drain electrodesindependently connected to the semiconductor layer. The gate wiring isconnected to the gate electrode, the source wiring is connected to thesource electrode, and the pixel electrode 414 is connected to the drainelectrode.

The gate wiring and gate electrode, the source wiring and sourceelectrode, and the drain electrode are typically formed by a processincluding forming a metal film such as a titanium, chromium, aluminum,or molybdenum film, a film of an alloy thereof, or a laminated filmthereof by sputtering or the like, and then patterning the film byphoto-etching or the like.

For example, the semiconductor layer is formed by a process includingforming a film of a semiconductor material such as amorphous silicon orpolysilicon by plasma CVE (Chemical Vapor Deposition) or the like andthen patterning the film by photo-etching or the like.

For example, the pixel electrodes 414 are formed by a process includingforming a film of a transparent electrically-conductive material such asindium tin oxide (ITO), indium zinc oxide, tin oxide, or zinc oxide bysputtering or the like and then pattering the film by photo-etching orthe like.

For example, the alignment film 415 is formed by a process includingapplying polyimide resin to form a film and rubbing the film.

On the other hand, in embodiment 1, the second substrate 42 (hereinafteralso referred to as the display surface side substrate) placed on theimage display side of the liquid crystal cell 4 includes a transparentsubstrate 421; a color filter 422 provided on the transparent substrate421; an overcoat layer (not shown) provided on the color filter 422; atransparent electrode (common electrode) 424 provided on the overcoatlayer and opposed to the pixel electrodes 414; and an alignment film 425provided on the transparent electrode (common electrode) 424.

The color filter 422 to be used is preferably configured to include ablack matrix for shielding light between colored patterns, and red,green and blue colored layers each corresponding to each pixel.

For example, the black matrix is made of chromium metal and has athickness of 100 to 150 nm. For example, the colored layers used aremade of a resin material colored with a dye or a pigment and have athickness of 1 to 3 μm. The pixel pattern arrangement used for thecolored layers may be a delta arrangement, a mosaic arrangement, or astripe arrangement. For example, the overcoat layer is made of acrylicresin, epoxy resin, or the like and has a thickness of 0.5 to 2 μm.

Examples of the method for manufacturing the color filter 422 include,but are not limited to, a staining method, a pigment dispersion method,a printing method, and an electro-deposition method.

For example, the common electrode 424 is formed by a process includingforming a film of a transparent electrically-conductive material such asindium tin oxide (ITO), indium zinc oxide, tin oxide, or zinc oxide bysputtering or the like, and then pattering the film by photo-etching orthe like.

For example, the liquid crystal layer 43 of the liquid crystal cell 4 ismade of a nematic liquid crystal molecule 431 having negative dielectricanisotropy (Δ∈<0). The liquid crystal layer 43 is driven by a voltageapplied in a direction substantially perpendicular to the substratesurface between the pixel electrode 414 of the backside substrate 41(first substrate 41) and the common electrode 424 of the display surfaceside substrate 42 (second substrate 42). Therefore, when the voltage isless than the threshold voltage, the long axis of the liquid crystalmolecule is oriented substantially perpendicular to the substratesurface, so that linearly polarized light incident on the back side doesnot undergo a birefringence effect when passing through the liquidcrystal layer 43 and therefore cannot pass through the second polarizer21 of the second polarizing plate 20 on the display surface side. Whenthe voltage becomes the threshold voltage or more, the long axis of theliquid crystal molecule 431 is tilted at a certain angle depending onthe magnitude of the voltage with respect to the substrate surface, sothat linearly polarized light incident on the back side undergoes abirefringence effect when passing through the liquid crystal layer 43and therefore can partially pass through the second polarizer 21 of thesecond polarizing plate 20 on the display surface side.

In the liquid crystal cell 4, because of the substrate structuredescribed above, the backside substrate 41 is less susceptible toelectrostatic decay (potential decay) after it is electrostaticallycharged, while the display surface side substrate 42 is more susceptibleto electrostatic decay (potential decay) than the backside substrate 41after it is electrostatically charged. Therefore, when the VA-typeliquid crystal cell 4 is used, the backside substrate 41 is a substrate(first substrate) to which a polarizing plate should be bonded first,and the display surface side substrate 42 is a substrate (secondsubstrate) to which a polarizing plate should be bonded subsequently.

The liquid crystal cell 4 is not restricted to a VA type, and it isconsidered that a TN (Twisted Nematic) type, a STN (Super-TwistedNematic) type, or an OCB (Optically Compensated Birefringence) type alsoshows the same tendency, because similarly to the VA type, they have abackside substrate containing pixel electrodes, a display surface sidesubstrate containing a common electrode, and a liquid crystal layer thatis driven by a voltage applied in a direction substantiallyperpendicular to the substrate surface between the pixel electrode andthe common electrode. Also in the case of a TN, STN or OCB type,therefore, it is considered to be necessary to bond a polarizing platefirst to the backside substrate and then to bond a polarizing plate tothe display surface side substrate as in the case of the VA type, sothat the effects of the invention can be obtained. Which of the backsidesubstrate or the display surface side substrate corresponds to the firstor the second substrate may be determined by the method described below.

Polarizing Plates

The first polarizing plate 10 includes at least a first polarizer 11(having an absorption axis in a direction parallel to the short side ofthe liquid crystal cell 4). The first polarizing plate 10 includes thefirst polarizer 11; first and second protective films 13 and 14 placedon both sides of the first polarizer 11, wherein the first protectivefilm is closer to the liquid crystal cell; a firstelectrically-conductive layer 12 placed on the inner side of the firstprotective film 13; a first pressure-sensitive adhesive layer 15 forbonding the first polarizing plate 10 to the first substrate 41 of theliquid crystal cell 4; and a first surface protecting film 17 placed onthe second protective film 14 with a first weak pressure-sensitiveadhesive layer 16 interposed therebetween.

The first polarizer 11 to be used may be any known conventionalpolarizer, and for example, a polyvinyl alcohol film with an iodinecomplex or a dichroic dye adsorbed thereon is preferably used. Forexample, the first protective film 13 and the second protective film 14to be used are each preferably, but not limited to, a film made oftriacetylcellulose resin, polyester resin, polycarbonate resin, cyclicpolyolefin resin, (meth) acrylic resin, or the like.

The first electrically-conductive layer 12 preferably has a surfaceresistance of 1.0×10¹² Ω/square or less, more preferably 1.0×10¹¹Ω/square or less. When the first electrically-conductive layer isprovided, the electrostatic charging of the first substrate (liquidcrystal cell) can be suppressed during the bonding of the first andsecond polarizing plates, so that the electrostatic charge on the liquidcrystal cell can be more quickly attenuated. The surface resistance maybe measured by the method as shown in examples below. Anelectrically-conductive layer is not necessarily formed in the firstpolarizing plate, and the effects of the invention can be obtained evenwhen a polarizing plate with no electrically-conductive layer formedtherein is bonded to the liquid crystal cell. It will be understood thatthe first electrically-conductive layer is formed at any location in thefirst polarizing plate, specifically, at any location from the firstsurface protecting film to the first pressure-sensitive adhesive layer.

The material of the first electrically-conductive layer 12 is notrestricted. The first electrically-conductive layer 12 may be made of ametal oxide such as ITO (Indium Tin Oxide) composed mainly of indiumoxide and doped with tin oxide; an electrically-conductive polymer suchas polyacetylene, polypyrrole, polythiophene, or polyphenylene vinylene;the electrically-conductive polymer and a halogen or a halide addedthereto; or an ionic surfactant.

The method of forming the first electrically-conductive layer 12 is alsonot restricted. For example, the first electrically-conductive layer 12of a metal oxide is preferably formed using vapor phase deposition suchas sputtering, vacuum deposition, ion plating, or plasma CVD, and thefirst electrically-conductive 12 of an electrically-conductive polymermay be formed using a known conventional coating method such as barcoating, blade coating, spin coating, reverse coating, die coating, orspraying.

The first electrically-conductive layer 12 preferably has a thickness of100 nm to 300 nm.

The second polarizing plate 20 includes at least a second polarizer 21(having an absorption axis in a direction parallel to the long side ofthe liquid crystal cell 4). In this embodiment, the second polarizingplate 20 includes the second polarizer 21; third and fourth protectivefilms 23 and 24 placed on both the inner and outer sides of the secondpolarizer 21; a second pressure-sensitive adhesive layer 25 for bondingthe second polarizing plate 20 to the second substrate 42 of the liquidcrystal cell 4; and a second surface protecting film 27 placed on thesecond protective film 24 with a second weak pressure-sensitive adhesivelayer 26 interposed therebetween.

While the second polarizing plate 20 may or may not have anelectrically-conductive layer, it preferably has anelectrically-conductive layer (second electrically-conductive layer) inorder to suppress the electrostatic charging of the second substrate 42(liquid crystal cell) during the bonding of the second polarizing plateand to attenuate the electrostatic charge on the liquid crystal cell 4more quickly. The structure of such an electrically-conductive layer maybe the same as that of the first electrically-conductive layer.

Besides the layers described above, the first or second polarizing platemay further include any other layer having an optical function, aphysical function or any other function, such as a brightnessenhancement layer, a retardation layer, or an anti-reflection layer, asneeded.

Continuous Manufacturing System

A system for continuously manufacturing the liquid crystal display panelY is described with reference to FIG. 2.

The system according to this embodiment for continuously manufacturingthe liquid crystal display panel includes liquid crystal cell supplymeans 50, first polarizing plate supply means 100 a, first polarizingplate bonding means 100 b, liquid crystal cell feed means 60, secondpolarizing plate supply means 200 a, second polarizing plate bondingmeans 200 b, liquid crystal display panel feed means 70, and inspectionmeans 80. In this embodiment, the liquid crystal cell supply means 50,the liquid crystal cell feed means 60, and the liquid crystal displaypanel feed means 70 form a continuous line 300, which includes a seriesof lines for feeding the liquid crystal cell and the liquid crystaldisplay panel, and the bonding means (first polarizing plate bondingmeans 100 b and second polarizing plate bonding means 200 b) and theinspection means 80 are arranged in the continuous line 300.

Liquid Crystal Cell Supply Means

The liquid crystal cell supply means 50 supplied the liquid crystal cell4 to the first polarizing plate bonding means 100 b. In this embodiment,the liquid crystal cell supply means 50 only includes a feedingmechanism 510, but such a configuration is non-limiting.

First Polarizing Plate Supply Means

The first polarizing plate supply means 100 a feeds a first belt-shapedfilm 61 from a first polarizing plate roll 6, which is a roll of thefirst belt-shaped film 61 including a first belt-shaped carrier film 62and a first belt-shaped polarizing plate formed on the first belt-shapedcarrier film 62, cuts the first belt-shaped polarizing plate atpredetermined intervals to form a first polarizing plate 10, peels offthe first polarizing plate 10 from the first belt-shaped carrier film 62by folding back the first belt-shaped carrier film 62, and supplies thefirst polarizing plate 10 to the first polarizing plate bonding means100 b. For the operation, the first polarizing plate supply means 100 aincludes first cutting means 130, first peeling means 140, and firsttake-up means 160.

The first cutting means 130 cuts the first belt-shaped polarizing plateat predetermined intervals to form the first polarizing plate 10 on thefirst belt-shaped carrier film 62. The first cutting means 130 may beconfigured to cut the first belt-shaped polarizing plate, which has awidth corresponding to the long side of the first substrate 41 of theliquid crystal cell 4, into a length corresponding to the short side ofthe first substrate 41 of the liquid crystal cell 4, or configured tocut the first belt-shaped polarizing plate, which has a widthcorresponding to the short side of the first substrate 41 of the liquidcrystal cell 4, into a length corresponding to the long side of thefirst substrate 41 of the liquid crystal cell 4. In this embodiment, thefirst cutting means 130 is configured to cut the first belt-shapedpolarizing plate, which has a width corresponding to the long side ofthe first substrate 41 of the liquid crystal cell 4, into a lengthcorresponding to the short side of the first substrate 41 of the liquidcrystal cell 4. For example, the first cutting means 130 may be acutter, a laser, or the like.

The first peeling means 140 inwardly folds back the first belt-shapedcarrier film 62 to peel off the first polarizing plate 10 from the firstbelt-shaped carrier film 62. In this embodiment, a sharp-ended knifeedge part is used as a non-limiting example of the first peeling means140.

The first take-up means 160 takes up the belt-shaped carrier film 62from which the first polarizing plate 10 is peeled off.

First Polarizing Plate Bonding Means

The first polarizing plate bonding means 100 b bonds the firstpolarizing plate 10 to the first substrate 41 of the liquid crystal cell4, wherein the liquid crystal cell 4 is supplied by the liquid crystalcell supply means 50, and the first polarizing plate 10 is supplied bythe first polarizing plate supply means 100 a. In this embodiment, thefirst polarizing plate bonding means 100 b includes a pair of bondingrollers (first bonding rollers) 150 a and 150 b.

Liquid Cell Feed Means

The liquid crystal cell feed means 60 transports and supplies, to thesecond polarizing plate bonding means 200 b, the liquid crystal cell 4with the first polarizing plate 10 bonded thereto by the firstpolarizing plate bonding means 100 b. In this embodiment, the liquidcrystal cell feed means 60 has a turning mechanism (not shown) forhorizontally turning by 90° the liquid crystal cell 4 with the firstpolarizing plate 10 bonded thereto. The liquid crystal cell feedingmechanism 60 may have a turnover mechanism for turning over the liquidcrystal cell 4 with the first polarizing plate 10 bonded thereto.Alternatively, the liquid crystal cell feeding mechanism 60 may includeonly a mechanism for feeding the liquid crystal cell 4 with the firstpolarizing plate 10 bonded thereto.

Second Polarizing Plate Supply Means

The second polarizing plate supply means 200 a feeds a secondbelt-shaped film 71 from a second polarizing plate roll 7, which is aroll of the second belt-shaped film 71 including a second belt-shapedcarrier film 72 and a second belt-shaped polarizing plate formed on thesecond belt-shaped carrier film 72, cuts the second belt-shapedpolarizing plate at predetermined intervals to form a second polarizingplate 20, peels off the second polarizing plate 20 from the secondbelt-shaped carrier film 72 by folding back the second belt-shapedcarrier film 72, and supplies the second polarizing plate 20 to thesecond polarizing plate bonding means 200 b. The second polarizing platesupply means 200 a includes second cutting means 230, second peelingmeans 240, and second take-up means 260. The second cutting means 230has the same configuration as the first cutting means, the secondpeeling means has the same configuration as the first peeling means, andthe second take-up means has the same configuration as the first take-upmeans. In this embodiment, the second cutting means 230 is configured tocut the second belt-shaped polarizing plate, which has a widthcorresponding to the short side of the second substrate 42 of the liquidcrystal cell 4, into a length corresponding to the long side of thesecond substrate 42 of the liquid crystal cell 4.

Second Polarizing Plate Bonding Means

The second polarizing plate bonding means 200 b bonds the secondpolarizing plate 20 to the second substrate 42 of the liquid crystalcell 4 to form a liquid crystal display panel Y, wherein the liquidcrystal cell 4 is supplied by the liquid crystal cell feed means 60, andthe second polarizing plate 20 is supplied by the second polarizingplate supply means 200 a. In this embodiment, the second polarizingplate bonding means 200 b includes a pair of bonding rollers (secondbonding rollers) 250 a and 250 b.

Liquid Crystal Display Panel Feed means

The liquid crystal display panel feed means 70 feeds the liquid crystaldisplay panel Y, which is formed by the second polarizing plate bondingmeans 200 b.

Inspection Means

The inspection means 80 optically inspects the liquid crystal displaypanel Y, which is fed by the liquid crystal display panel feed means 70,without applying a voltage to the liquid crystal display panel Y (morespecifically, the liquid crystal layer 43). In this embodiment, theinspection means 80 includes a transmitted light inspection means havinga light source (light irradiation means) 31 that is placed on one sideof the liquid crystal display panel feed means 70 (on a lower side inthe case shown in FIG. 2) to irradiate light to the lower surface of theliquid crystal display panel Y; and a CCD cameral (imaging means) 33that is placed on the other side of the liquid crystal display panel 70(on an upper side in the case shown in FIG. 2) to image the liquidcrystal display panel Y irradiated with the light source (lightirradiation means) 31. The presence or absence of foreign matter or airvoids interposed between the polarizing plate and the liquid crystalcell is determined based on the amount of transmitted light detected bythe CCD camera (imaging means) 33. Besides the transmitted lightinspection means, the inspection means 80 may further include reflectedlight inspection means for optically inspecting the liquid crystaldisplay panel Y by irradiating light to one side of the liquid crystaldisplay panel Y and detecting light reflected from the one side of theliquid crystal display panel Y. After the second polarizing plate isbonded, the inspection means 80 is preferably placed within 1 minute,more preferably within 40 seconds, even more preferably within 20seconds, in particular, preferably within 10 seconds, in the positionwhere the inspection will be started.

For example, the inspection means 80 may be configured as lineinspection means 81 or area inspection means 82. The line inspectionmeans 81 is described with reference to FIGS. 6A and 6B. The lineinspection means 81 includes a light source (light irradiation means)811 that is placed on one side of the liquid crystal display panel feedmeans 70 (on a lower side in the case shown in FIG. 6A) to irradiatelight to the lower surface of the liquid crystal display panel Y; alight receiving sensor (imaging means) 812 that is placed on the otherside of the liquid crystal display panel feed means 70 (an upper side inthe case shown in FIG. 6A) to image the liquid crystal display panel Yin a line mode, wherein the liquid crystal display panel Y is beingirradiated with the light source (light irradiation means) 811 and beingfed by the liquid crystal display panel feed means 70 in a directionfrom the feed-in side to the feed-out side along the feed line; an imageprocessing unit 813 that sequentially stores, in a memory, line imagedate taken by the light receiving sensor 812 and performs imageprocessing on a group of line image data stored in the memory; a controlunit 814 that determines the presence or absence of defects such asforeign bodies or air voids interposed between the polarizing plate andthe liquid crystal cell based on the image date having undergone imageprocessing in the image processing unit 813; and a storage unit 815 thatstores the result of the determination in the control unit 814 (whetherthe product is normal or defective) together with identificationinformation about the liquid crystal display panel.

A specific inspection process is described with reference to the processflow shown in FIG. 6B. First, the liquid crystal display panel Y isstopped at a position for waiting for the inspection (see “Position forwaiting for inspection” in part (c) of FIG. 6A). The control unit 814controls the liquid crystal display panel feed means 70 for feeding theliquid crystal display panel Y to start the feeding of the liquidcrystal display panel Y (S1) and the inspection by the line inspectionmeans 81 (S2). The light receiving sensor 812 is arranged to extend in aline shape (linearly) in a direction perpendicular to the feed directionof the liquid crystal display panel Y and images, in a line mode, theliquid crystal display panel Y being fed in a direction from the feed-inside to the feed-out side along the feed line (S3) (see Inspectionposition in part (c) of FIG. 6A). The light receiving sensor 812 takes aline-shaped image of the transmitted light produced by the light source811. Referring to part (b) of FIG. 6A, the normal field of view of thelight receiving sensor 812 is narrowed to form an inspection area sothat line image date can be obtained. The image processing unit 813sequentially stores, in the memory (not shown), the line image datataken by the light receiving sensor 812. The liquid crystal displaypanel Y is fed to the inspection end position (see Inspection endposition in part (c) of FIG. 6A) and stopped (S5). The amount of thefeed has been previously determined, and the liquid crystal displaypanel feed means 70 performs intermittent feeding. The image processingunit 813 then performs image processing on a group of the line imagedata stored in the memory (S6). The control unit 814 determines thepresence or absence of defects such as foreign bodies or air voidsinterposed between the polarizing plate and the liquid crystal cellbased on the image data having undergone the image processing in theimage processing unit 813 (S7). When the control unit 814 determines theproduct to be normal, the control unit 814 stores, in the storage unit815, the information that the liquid crystal display panel Y isdetermined to be a normal product (S8). The liquid crystal display panelY determined to be a normal product is fed to a non-defective productport (S9). On the other hand, when the product is determined to bedefective by the control unit 814, the control unit 814 stores, in thestorage unit 815, the information that the liquid crystal display panelY is determined to be a defective product (S10). The liquid crystaldisplay panel Y determined to be a defective product is fed to adefective product port (S11).

Next, a description is given of the area inspection means 82 withreference to FIGS. 7A and 7B. The area inspection means 82 includes alight source (light irradiation means) 821 that is placed on one side ofthe liquid crystal display panel feed means 70 (on a lower side in thecase shown in FIG. 7A) to irradiate light to the lower surface of theliquid crystal display panel Y; a light receiving sensor (imaging means)822 that is placed on the other side of the liquid crystal display panelfeed means 70 (an upper side in the case shown in FIG. 7A) to image theliquid crystal display panel Y irradiated with the light source (lightirradiation means) 821; an image processing unit 823 that stores, in amemory, image date taken by the light receiving sensor 822 and performsimage processing on the image data stored in the memory; a control unit824 that determines the presence or absence of defects such as foreignbodies or air voids interposed between the polarizing plate and theliquid crystal cell based on the image date having undergone imageprocessing in the image processing unit 823; and a storage unit 825 thatstores the result of the determination in the control unit 824 (whetherthe product is normal or defective) together with identificationinformation about the liquid crystal display panel.

A specific inspection process is described with reference to the processflow shown in FIG. 7B. First, the liquid crystal display panel Y isstopped at a position for waiting for the inspection (see “Position forwaiting for inspection” in part (c) of FIG. 7A). The control unit 824controls the liquid crystal display panel feed means 70 for feeding theliquid crystal display panel Y to start the feeding of the liquidcrystal display panel Y (S21) to the inspection position and to stop theliquid crystal display panel Y at the inspection position (S22). Thelight receiving sensor 822 images the liquid crystal display panel Ybeing stopped (S23) (see Inspection position in part (c) of FIG. 7A). Asshown in part (b) of FIG. 7A, the light receiving sensor 822 takes, in alarge inspection area, an image of the transmitted light produced by thelight source 821. For example, when the liquid crystal display panel asthe inspection object is too large, partial imaging may be performedplural times using a single light receiving sensor. In this case, thelight receiving sensor may be shifted and stopped for imaging as needed,or the liquid crystal display panel Y may be shifted and stopped forimaging as needed. In an alternative method, a plurality of lightreceiving sensors may be placed so that the liquid crystal display panelcan be imaged in parts across the area to be imaged. The imageprocessing unit 823 stores, in the memory (not shown), the image datataken by the light receiving sensor 822 (S24). The image processing unit823 performs image processing on the image data stored in the memory(S25). The control unit 824 determines the presence or absence ofdefects such as foreign bodies or air voids interposed between thepolarizing plate and the liquid crystal cell based on the image datahaving undergone the image processing in the image processing unit 823(S26). When the control unit 824 determines the product to be normal,the control unit 824 stores, in the storage unit 825, the informationthat the liquid crystal display panel Y is determined to be a normalproduct (S27). After the determination process, the liquid crystaldisplay panel Y is fed to the inspection end position (see Inspectionend position in part (c) of FIG. 7A) and stopped. The amount of the feedhas been previously determined, and the liquid crystal display panelfeeding means 70 performs intermittent feeding. The liquid crystaldisplay panel Y determined to be a normal product is then fed to anon-defective product port (S28). On the other hand, when any defect isdetected, the control unit 824 calculates the position of the defect(S29), stores the position of the defect in the storage unit 825 (S30),and determines the liquid crystal display panel Y to be a defectiveproduct (S31). After the determination process, the liquid crystaldisplay panel Y is fed to the inspection end position (see Inspectionend position in part (c) of FIG. 7A) and stopped. Subsequently, theliquid crystal display panel Y determined to be a defective product isfed to a defective product port (S32).

The system according to this embodiment for continuously manufacturing aliquid crystal display panel is configured to first bond the firstpolarizing plate, which has an electrically-conductive layer, to thefirst substrate (backside substrate), which is less susceptible toelectrostatic decay after it is electrostatically charged, and then bondthe second polarizing plate to the second substrate (display surfaceside substrate) which is more susceptible to electrostatic decay afterit is electrostatically charged. Therefore, the electrostatic charge onthe liquid crystal cell can be quickly attenuated when the first andsecond polarizing plates are bonded, so that the inspection(non-lighting inspection) of the liquid crystal display panel can bequickly performed without the adverse effect of the electrostatic chargeon the liquid crystal cell after the bonding of the polarizing plates.As a result, high-quality VA-type liquid crystal display panels can becontinuously manufactured at high speed, which makes it possible tosubstantially increase the production efficiency. In addition, there isno need to perform re-inspection, which makes it possible to reduce thenumber of processes and to make the process control simpler thanconventional techniques. The liquid crystal display panel manufacturingline can also be shortened.

Continuous Manufacturing Method

The method according to this embodiment for continuously manufacturing aliquid crystal display panel includes: a bonding step includingsequentially bonding a first polarizing plate and a second polarizingplate to both surfaces of a liquid crystal cell to form a liquid crystaldisplay panel, wherein the first and second polarizing plates are drawnand supplied from a first polarizing plate roll and a second polarizingplate roll, respectively; and an inspection step including opticallyinspecting the liquid crystal display panel formed in the bonding step,wherein the bonding step and the inspection step are performed in aseries of feed lines for feeding the liquid crystal cell and the liquidcrystal display panel (in a continuous line). The bonding step includes:a first polarizing plate bonding step including bonding the firstpolarizing plate to a first substrate of the liquid crystal cell,wherein the first substrate is relatively less susceptible toelectrostatic decay; and a second polarizing plate bonding stepincluding bonding the second polarizing plate to a second substrate ofthe liquid crystal cell, wherein the second substrate is relatively moresusceptible to electrostatic decay. In this embodiment, the firstpolarizing plate bonding step is followed by the second polarizing platebonding step. The inspection step also includes optically inspecting theliquid crystal display panel, which is formed by the first and secondpolarizing plate bonding steps, without applying a voltage to the liquidcrystal display panel (non-lighting inspection step). The firstpolarizing plate bonding step and the second polarizing plate bondingstep preferably include sequentially bonding the first polarizing plateand the second polarizing plate to the liquid crystal cell, whilefeeding the liquid crystal cell in a direction from the feed-in side tothe feed-out side along the feed line. The inspection step preferablyincludes performing the inspection in a line mode, while feeding theliquid crystal display panel, which is formed by the bonding steps, in adirection from the feed-in side to the feed-out side along the feedline.

First Polarizing Plate Bonding Step

In the first polarizing plate bonding step, the first polarizing platedrawn and supplied from the first polarizing plate roll is bonded to thefirst substrate of the liquid crystal cell. In this embodiment, a firstbelt-shaped film 61 is first drawn from a first polarizing plate roll 6,which is a roll of the first belt-shaped film 61 including a firstbelt-shaped carrier film 62 and a first belt-shaped polarizing plateformed on the first belt-shaped carrier film 62. Subsequently, the firstbelt-shaped polarizing plate is cut, while the first belt-shaped carrierfilm 62 is left (uncut), so that a first polarizing plate 10 is formedon the first belt-shaped carrier film 62. Subsequently, the firstpolarizing plate 10 is peeled off from the first belt-shaped carrierfilm 62, for example, by hooking and reversing (backward feeding) thefirst belt-shaped carrier film 62. Subsequently, the first polarizingplate 10 from which the first belt-shaped carrier film 62 is peeled off(or from which the first belt-shaped carrier film 62 is being peeledoff) is bonded to the first substrate 41 of the liquid crystal cell 4.

Second Polarizing Plate Bonding Step

In the second polarizing plate bonding step, the second polarizing platedrawn and supplied from the second polarizing plate roll is bonded tothe second substrate of the liquid crystal cell. In this embodiment, asecond belt-shaped film 71 is first drawn from a second polarizing plateroll 7, which is a roll of the second belt-shaped film 71 including asecond belt-shaped carrier film 72 and a second belt-shaped polarizingplate formed on the second belt-shaped carrier film 72. Subsequently,the second belt-shaped polarizing plate is cut, while the secondbelt-shaped carrier film 72 is left (uncut), so that a second polarizingplate 20 is formed on the second belt-shaped carrier film 72.Subsequently, the second polarizing plate 20 is peeled off from thesecond belt-shaped carrier film 72, for example, by hooking andreversing (backward feeding) the second belt-shaped carrier film 72.Subsequently, the second polarizing plate 20 from which the secondbelt-shaped carrier film 72 is peeled off (or from which the secondbelt-shaped carrier film 72 is being peeled off) is bonded to the secondsubstrate 42 of the liquid crystal cell 4 to form a liquid crystaldisplay panel Y.

Inspection Step

In the inspection step, the liquid crystal display panel Y formed by thebonding steps (the first polarizing plate bonding step and the secondpolarizing plate bonding step) is optically inspected with no voltageapplied to the liquid crystal display panel Y (the liquid crystal cell,more specifically, the liquid crystal layer 43). In this embodiment,light is irradiated to one side of the liquid crystal display panel Y,and light transmitted through the liquid crystal display panel Y isreceived at the other side of the liquid crystal display panel Y so thata transmitted light inspection step can be performed to opticallyinspect the liquid crystal display panel Y.

In this embodiment, the bonding steps (the first polarizing platebonding step and the second polarizing plate bonding step) and theinspection step are performed in a series of feed lines for feeing theliquid crystal cell and the liquid crystal display panel (in acontinuous line). In the bonding steps, the electrostatic charging ofthe liquid crystal cell 4 is inevitable. In this embodiment, however,the first polarizing plate bonding step is followed by the secondpolarizing plate bonding step, so that the electrostatic charge on theliquid crystal cell 4 can be quickly attenuated. As a result, in thecontinuous line, the optical inspection (non-lighting inspection) of theliquid crystal display panel Y can be quickly performed without theinfluence of the electrostatic charge on the liquid crystal cell 4 afterthe bonding of the polarizing plates, so that high-quality liquidcrystal display panels Y can be continuously manufactured at high speed.

When the line inspection means 81 or the area inspection means 82 isused, the inspection step can be performed as a line inspection step oran area inspection step. Particularly to improve the high-speedcontinuous productivity of high-quality liquid crystal display panels,the inspection step is preferably performed as a line inspection step.

Although the mechanism of how the invention is effective is not clear,it is considered that in the VA-type liquid crystal cell for thisembodiment, the backside substrate (first substrate) is less susceptibleto electrostatic decay, once it is electrostatically charged, so thatthe electrostatic charge produced by the friction with a supportingroller remains on the liquid crystal cell, because the backsidesubstrate (first substrate) has switching elements (thin filmtransistors) between the circuit part such as gate wiring and the pixelelectrodes.

Specifically, in the backside substrate (first substrate), theelectrostatic charge accumulated on the surface of the substrate byelectrostatic induction during the electrostatic charging is graduallytransferred to the pixel electrodes or the circuit part, so that theelectrostatic charge builds up in both sites. Thereafter, theelectrostatic charge is quickly transferred from the circuit part duringdischarge. In contrast, the electrostatic charge on the pixel electrodescannot move toward the circuit part and therefore is more likely toremain, because the pixel electrodes are electrically isolated from thecircuit part by the switching elements (thin film transistors) in thenon-driving state. It is considered that due to these factors, thebackside substrate in this embodiment is less susceptible toelectrostatic decay, after it is electrostatically charged. It isconsidered that in the continuous manufacturing system and method ofthis embodiment, a polarizing plate is bonded to the backside substrate(first substrate) earlier than to the display surface side substrate(second substrate), so that friction between the first substrate and thebonding roller is prevented and that the first substrate itself isinhibited from being electrostatically charged, which makes it possibleto quickly attenuate the electrostatic charge on the liquid crystalcell.

Other Manufacturing Methods

In this embodiment, the first polarizing plate is bonded to the liquidcrystal cell from the lower side, and the second polarizing plate isbonded to the liquid crystal cell from the upper side. However, thedirection of the bonding of the first and second polarizing plates isnot limited to this mode. For example, after the first polarizing plateis bonded to the liquid crystal cell from the lower side, the liquidcrystal cell may be turned upside down, and the second polarizing platemay also be bonded to the liquid crystal cell from the lower side.

Alternatively, the timing of the cutting of the belt-shaped polarizingplat may be after the bonding of the belt-shaped polarizing plate to theliquid crystal cell. In this case, the first belt-shaped film is drawnfrom the first polarizing plate roll, and the first belt-shapedpolarizing plate is bonded to the first substrate of the liquid crystalcell using bonding means, after (or while) the first belt-shapedpolarizing plate is peeled off from the first belt-shaped carrier film.Subsequently, the first belt-shaped polarizing plate is cut into a piecedepending on the size of the liquid crystal cell using cutting means, sothat a piece of the first polarizing plate is formed on the firstsubstrate of the liquid crystal cell. The second belt-shaped film isdrawn from the second polarizing plate roll, and the second belt-shapedpolarizing plate is bonded to the second substrate of the liquid crystalcell using bonding means, after (or while) the second belt-shapedpolarizing plate is peeled off from the second belt-shaped carrier film.Subsequently, the second belt-shaped polarizing plate is cut into apiece depending on the size of the liquid crystal cell using cuttingmeans, so that a piece of the second polarizing plate is formed on thesecond substrate of the liquid crystal cell. Subsequently, the liquidcrystal display panel is optically inspected (preferably in a line mode)with no voltage applied to the liquid crystal display panel.

Other Polarizing Plate Rolls

In this embodiment, the first and second belt-shaped polarizing plateseach have an absorption axis in the longitudinal direction. However, thedirection of the absorption axis of each of the first and secondbelt-shaped polarizing plates is not limited thereto. Alternatively, forexample, the first belt-shaped polarizing plate may have an absorptionaxis in the transverse (width) direction, and the second belt-shapedpolarizing plate may have an absorption axis in the longitudinaldirection. In this case, the turning mechanism for horizontally turningby 90° the liquid crystal cell with the first polarizing plate bondedthereto may be omitted as appropriate.

The first and second belt-shaped polarizing plates in the first andsecond polarizing plate rolls may also have previously undergonecutting. Specifically, the first and second polarizing plate rolls to beused may be so-called scored polarizing plate rolls. In this case, thefirst cutting means (first cutting step) and the second cutting means(second cutting step) are unnecessary, so that the tact time can bereduced.

Embodiment 2

A description is given of a case where an in-plane switching (IPS)-typeliquid crystal cell is used.

FIG. 3 is a schematic cross-sectional view of a liquid crystal displaypanel Y with an IPS-type liquid crystal cell. In FIG. 4, the sameelements are represented by the same reference characters as in FIG. 1,and a repeated description thereof will be omitted as appropriate. Asshown in FIG. 4, an IPS-type liquid crystal cell 4′ is configured tohave a liquid crystal layer 43′ placed between a pair of substrates 41′and 42′ similarly to other liquid crystal cells. The display surfaceside substrate 42′ located on the display surface side of the liquidcrystal cell 4′ does not have any electrically-conductive componentssuch as pixel electrodes and a common electrode. In contrast, thebackside substrate 41′ located on the back side of the liquid crystalcell 4′ is configured to have a common electrode and pixel electrodesfor driving the liquid crystal layer 43′, so that the liquid crystallayer 43′ is driven by an electric field applied between the commonelectrode and the pixel electrodes, specifically, in a directionsubstantially parallel to the surface of the substrate.

Specifically, the backside substrate 41′ includes a transparentsubstrate 411 of glass, plastic or the like; a circuit part that isprovided on the transparent substrate 411 and includes a plurality ofgate wirings and a plurality of common electrode wirings, and aplurality of source wirings arranged perpendicular to the gate wiringsand the common electrode wirings and provided thereon with a gateinsulating film interposed therebetween; thin film transistors (TFT) 412provided as a plurality of switching elements at the intersections ofthe gate wirings and the source wirings; a protective film 413 providedon the switching elements (thin film transistors) 412; a plurality oftransparent electrodes (pixel electrodes) 414 provided on the protectivefilm 413 and connected to the switching elements 412, respectively, viacontact holes formed through the protective film 413; a plurality ofcommon electrodes 416 provided on the protective film 413 and connectedto the common electrode wirings, respectively, via contact holes formedthrough the gate insulating film and the protective; and an alignmentfilm 415 provided on the transparent electrodes (pixel electrodes) 414and the common electrodes 416.

The thin film transistors 412 each include a gate electrode, asemiconductor layer opposed to the gate electrode with a gate insulatingfilm interposed therebetween, and source and drain electrodesindependently connected to the semiconductor layer. The gate wiring isconnected to the gate electrode, the source wiring is connected to thesource electrode, and the pixel electrode 414 is connected to the drainelectrode.

On the other hand, the display surface side substrate 42′ includes atransparent substrate 421 of glass, plastic, or the like; a color filter422 provided on the transparent substrate 421; an overcoat layer (notshown) provided on the color filter 422; and an alignment film 425provided on the overcoat layer.

The liquid crystal layer 43′ of the liquid crystal cell 4′ is generallymade of a nematic liquid crystal molecule 431′ having positivedielectric anisotropy (Δ∈>0) or negative dielectric anisotropy (Δ∈<0).The liquid crystal layer 43′ is driven by a voltage applied in adirection substantially parallel to the substrate surface between thepixel electrode 414 and the common electrode 416. Therefore, when thevoltage is less than the threshold voltage, the long axis of the liquidcrystal molecule 431′ is parallel to the substrate surface and parallelor perpendicular to the absorption axis of the first polarizer 11 of thefirst polarizing plate 10, so that linearly polarized light incident onthe back side does not undergo a birefringence effect when passingthrough the liquid crystal layer 43′. When the voltage becomes thethreshold voltage or more, the long axes of most of the liquid crystalmolecules 431, exclusive of those in the vicinity of substrate surface,are rotated in an in-plane direction parallel to the substrate surfaceat a certain angle depending on the magnitude of the voltage (and tiltedwith respect to the absorption axis of the first polarizer 11 of thefirst polarizing plate 10), so that linearly polarized incident lightundergoes a birefringence effect and is changed into ellipticallypolarized light. As a result, a certain amount of light, which dependson the rotation angle of the liquid crystal molecules, passes throughthe first polarizer 11 of the first polarizing plate 10.

In such an IPS-type liquid crystal cell used, the display surface sidesubstrate 42′ has a structure that is less susceptible to electrostaticdecay than the backside substrate 41′, after it is electrostaticallycharged, because it does not have electrically-conductive componentssuch as pixel and common electrodes. Therefore, when an IPS-type liquidcrystal cell is used, the display surface side substrate 42′ is asubstrate (first substrate) to which a polarizing plate should be bondedfirst, and the backside substrate 41′ is a substrate (second substrate)to which a polarizing plate should be bonded subsequently.

In the system and method according to embodiment 2 for continuouslymanufacturing a liquid crystal display panel, the display surface sidesubstrate corresponds to the first substrate, the display surface sidepolarizing plate corresponds to the first polarizing plate, the backsidesubstrates corresponds to the second substrate, and the backsidepolarizing plate corresponds to the second polarizing plate. Otherfeatures are the same as those of the continuous manufacturing methodand system in Embodiment 1 above, and therefore a description thereof isomitted here.

In the system and method according to embodiment 2 for continuouslymanufacturing a liquid crystal display panel, the above procedure isperformed, specifically, the display surface side substrate 42′ is usedas the first substrate, to which the first polarizing plate is bonded,and subsequently, the backside substrate 41′ is used as the secondsubstrate, to which the second polarizing plate is bonded. This makes itpossible to quickly attenuate the electrostatic charge on the liquidcrystal cell 4′ when the first and second polarizing plates are bonded,so that the inspection of the liquid crystal display panel can bequickly performed without the adverse effect of the electrostatic chargeon the liquid crystal cell after the bonding of the polarizing plates.As a result, high-quality IPS-type liquid crystal display panels can becontinuously manufactured at high speed, which makes it possible tosubstantially increase the production efficiency.

Although the mechanism of how this embodiment is effective is not clear,it is considered that in embodiment 2 where an IPS-type liquid crystalcell is used, the display surface side substrate is less susceptible toelectrostatic decay, once it is electrostatically charged, so that theelectrostatic charge produced by the friction with a bonding rollerremains on the liquid crystal cell, because the display surface sidesubstrate does not have electrically-conductive components such as pixeland common electrodes. It is considered that in the continuousmanufacturing system and method according to embodiment 2, a polarizingplate is bonded to the display surface side substrate (first substrate)earlier than to the backside substrate (second substrate), so thatfriction between the bonding roller and the display surface sidesubstrate having the above structure is prevented and that the firstsubstrate itself is inhibited from being electrostatically charged,which makes it possible to quickly attenuate the electrostatic charge onthe liquid crystal cell.

The IPS type may also have the problem of electrostatic destruction ofswitching elements (thin film transistors). It is considered that themechanism of destruction of switching elements in a liquid crystal cellinvolves allowing excessive current to flow through switching elementswhen the electrostatic charge accumulated on the display surface sidesubstrate (first substrate) is discharged toward the backside substrate(second substrate), so that the switching elements are destroyed. It isconsidered that in the continuous manufacturing system and methodaccording to this embodiment, such electrostatic destruction ofswitching elements is also suppressed.

In an embodiment of the invention, as long as the effects of theinvention are attained, any appropriate means (step) may be interposedbetween the respective steps (for example, between the second polarizingplate bonding means (the second polarizing plate bonding step) and theinspection means (the inspection step)). Any other means (step) may alsobe provided before the first polarizing plate bonding means (the firstpolarizing plate bonding step), before the second polarizing platebonding means (the second polarizing plate bonding step), or after theinspection means (the inspection step).

EXAMPLES Measurement of Electrostatic Decay of Liquid Crystal CellSubstrate

Electrostatic decay after electrification was measured for each of a CFsubstrate (color filter-containing substrate) and a TFT substrate (thinfilm transistors-containing substrate), each of which was a component ofa VA-type liquid crystal cell, and another CF substrate and another TFTsubstrate, each of which was a component of an IPS-type liquid crystalcell. The TFT substrate and the CF substrate were each separated bycutting from the joint in the liquid crystal cell, and the liquidcrystal deposited on the inner side of each substrate was wiped off withalcohol. For the measurement, both ends of the substrate was mounted andfixed on a PTFE (polytetrafluoroethylene) support. Thereafter, alaminated disc (0.8 mm thick, 250 mm φ), which was formed by stacking aPTFE disc and a SUS 304 disc, was electrostatically charged by rubbingthe SUS 304 disc side several times with a cloth, and the SUS 304 discwas attached to the fixed substrate and then separated from thesubstrate. While a series of these procedures was performed, the amountof electrostatic charge on the substrate was measured using anelectrostatic charge meter (IZH10 manufacture by SMC Corporation) fromthe back side opposite to the attached surface of the substrate. Theresults are shown in Table 1 below, FIG. 4 (the result on the VA-type),and FIG. 5 (the result on the IPS-type).

TABLE 1 Initial Liquid amount of During After electrostatic crystalelectrostatic electrostatic charging (s) cell charge charging 0 30 60 90120 180 240 VA type TFT 0.1 5.8 2.1 1.4 1.1 0.9 0.5 0.2 0.1 substrate(First substrate) CF 0.05 6.1 0.05 0.05 0.05 0.05 0.00 0.05 0.05substrate (Second substrate) IPS TFT 0.08 6.8 0.6 0.09 0.08 0.06 0.050.05 0.02 type substrate (Second substrate) CF 0.1 6.5 5.9 5.1 4.3 3.52.2 1.8 0.8 substrate (First substrate)

Table 1 and FIG. 4 show that even after the PTFE disc was separated, theTFT substrate for the VA-type liquid crystal cell remainedelectrostatically charged for a while. In contrast, it was found thatimmediately after the PTFE disc was separated, the CF substrate for theVA-type liquid crystal cell returned to the initial state. In theVA-type liquid crystal cell used in this test, therefore, the TFTsubstrate has such properties that it is less susceptible toelectrostatic decay after electrostatically charged, and thereforecorresponds to the first substrate, and the CF substrate has suchproperties that it is susceptible to electrostatic decay afterelectrostatically charged, and therefore corresponds to the secondsubstrate.

Table 1 and FIG. 5 show that the TFT substrate and the CF substrate forthe IPS-type liquid crystal cell have a reverse tendency to thesubstrates for the VA-type liquid crystal cell. Namely, in the IPS-typeliquid crystal cell used in the test, the CF substrate has suchproperties that it is less susceptible to electrostatic decay afterelectrostatically charged, and therefore corresponds to the firstsubstrate, and the TFT substrate has such properties that it issusceptible to electrostatic decay after electrostatically charged, andtherefore corresponds to the second substrate.

The examples and the comparative examples below were performed using theVA-type liquid crystal cell, in which a test was performed using the TFTsubstrate as the first substrate and using the CF substrate as thesecond substrate.

Example 1

The continuous manufacturing system shown in FIG. 2 was used. A firstpolarizing plate with a width corresponding to the long side of theVA-type liquid crystal cell was bonded to the liquid crystal cell (thefirst polarizing plate bonding step), and then the liquid crystal cellwas horizontally turned by 90° and aligned. Subsequently, a secondpolarizing plate with a width corresponding to the short side of theliquid crystal cell was bonded to the liquid crystal cell (the secondpolarizing plate bonding step). In this manner, 2,000 liquid crystaldisplay panels were continuously manufactured. The speed at which eachpolarizing plate was bonded and the speed at which the liquid crystalcell and the liquid crystal display panel were fed were 200 mm/second.The materials and apparatuses used were as described below. The surfaceresistance of the electrically-conductive layer contained as a part inthe polarizing plate was measured according to JIS K 6911, 5.13.Specifically, the polarizing plate raw material was cut into a testpiece with a size of 150 mm×150 mm, and the surface resistance of thetest piece was measured using Hiresta UP (a high resistance/lowefficiency meter, model: MCP-HT450) manufactured by Mitsubishi ChemicalAnalytech Co., Ltd. and a probe (model: MCP-SWB01). The bonding speedwas the measured value of the speed at which the polarizing plate andthe liquid crystal cell passed between the bonding roller and thesupporting roller described below. Therefore, the polarizingplate-bonding speed was equal to the liquid crystal cell-feed speed.

Materials and Apparatuses Used

The liquid crystal cell was of a vertical alignment type (with a screensize of 32 inches). The first polarizing plate roll and the secondpolarizing plate roll were each VEG1724DU-AC (trade name) manufacturedby NITTO DENKO CORPORATION (containing an electrically-conductive layerwith a surface resistance of 1.0×10¹¹ Ω/square and a thickness of 150μm), and the structure and composition of the first and secondpolarizing plates were as shown in FIG. 1. The bonding roller (on thebonding side) was Model LM4070E manufactured by Katsura Roller Mfg. Co.,Ltd., which was an electrically-conductive silicone roller with ahardness of 70°, a surface resistance of 1.0×10⁶ Ω/square, and a rollerdiameter of 100 mm. The supporting roller (on the support side) wasModel BLACK EC-N970 manufactured by Katsura Roller Mfg. Co., Ltd., whichwas an electrically-conductive urethane roller with a hardness of 70°, asurface resistance of 1.0×10⁸ Ω/square, and a roller diameter of 200 mm.

Examples 2 to 4

Two thousand liquid crystal display panels were manufactured as inexample 1, except that the polarizing plate-bonding speed and the liquidcrystal cell and liquid crystal display panel-feed speed were 150mm/second (Example 2), 100 mm/second (Example 3), or 50 mm/second(example 4).

Comparative Example 1

Two thousand liquid crystal display panels were manufactured as inexample 1, except that the bonding order was reverse to that in example1, namely, the first polarizing plate bonding step was performed afterthe second polarizing plate bonding step.

Comparative Examples 2 to 4

Two thousand liquid crystal display panels were manufactured as incomparative example 1, except that the polarizing plate-bonding speedand the liquid crystal cell and liquid crystal display panel-feed speedwere 150 mm/second (comparative example 2), 100 mm/second (comparativeexample 3), or 50 mm/second (comparative example 4).

Comparative Example 5

Two thousand liquid crystal display panels were manufactured as incomparative example 1, except that the first polarizing plate bondingstep and the inspection step were separated from each other based on theresult of the measurement of the amount of electrostatic charge on theliquid crystal cell (Table 1 and FIG. 4) and that the time intervalbetween the first polarizing plate bonding step and the inspection stepwas 600 seconds.

Measurement of Amount of Electrostatic Charge

In the examples and the comparative examples, immediately after eachbonding step, an electrostatic charge meter (model SK-200 manufacturedby KEYENCE CORPORATION) was placed to measure the amount ofelectrostatic charge after the bonding, and the average value wascalculated for the 2,000 liquid crystal display panels. The results areshown in Table 3 below.

Evaluation in Inspection Step

The liquid crystal display panels manufactured in each of the examplesand the comparative examples were subjected to the inspection step usingan optical inspection apparatus placed downstream of the later bondingstep. In the inspection step, light was irradiated to the liquid crystaldisplay panel from its lower surface side with no voltage applied to theliquid crystal display panel, while the liquid crystal display panel wasfed. Above the upper side of the liquid crystal display panel, aplurality of CCD cameras (line sensor cameras) were arranged in a linepattern (linearly) along a direction perpendicular to the feed directionof the liquid crystal display panel. Transmission of light, which shouldotherwise be blocked in the normal state, was detected in a line patternusing the CCD cameras, and image analysis was performed based on theresult of the detection.

Table 2 below shows the conditions of each bonding step and theinspection step, and the time required to perform each step.

TABLE 2 Feed speed Time required Time required (Bonding to bond the tobond the Inspection Total speed) first piece Intervals (s) second pieceInterval (s) time time (mm/s) (s) Feeding Turning Feeding Alignment (s)Feeding (s) (s) Example 1 200 8 5 8 5 8 10 8 8 60 Comparative Example 1Example 2 150 11 7 11 7 11 13 11 11 80 Comparative Example 2 Example 3100 16 10 16 10 16 20 16 16 120 Comparative Example 3 Example 4 50 32 2032 20 32 40 32 32 240 Comparative Example 4 Comparative 200 8 5 8 5 8 10600 8 652 Example 5

The case where at least one piece was determined to be defective due tothe electrostatic charge on the liquid crystal cell (uneven alignment ofthe liquid crystal molecules) was evaluated as “x”, and the case whereno piece was determined to be defective was evaluated as “∘”. Theresults are shown in Table 3 below.

TABLE 3 Feed Amount (kV) of Amount (kV) of speed Amount (kV) ofelectrostatic electrostatic Evaluation (Bonding electrostatic chargeafter charge after in speed) charge before bonding of the bonding of theinspection Total time (mm/s) bonding first piece second piece step (s)Example 1 200 0.02 0.12 0.08 ◯ 60 Example 2 150 0.04 0.09 0.11 ◯ 80Example 3 100 0.05 0.08 0.21 ◯ 120 Example 4 50 0.01 0.11 0.17 ◯ 240Comparative 200 0.02 1.77 1.91 X 60 Example 1 Comparative 150 0.06 0.561.98 X 80 Example 2 Comparative 100 0.03 1.92 2.07 X 120 Example 3Comparative 50 0.05 1.61 1.88 X 240 Example 4 Comparative 200 0.02 1.781.93 ◯ 652 Example 5

As shown in Table 3, a product or products were determined to bedefective due to the electrostatic charge on the liquid crystal cell inthe inspection step in Comparative Examples 1 to 4 where the CFsubstrate (second substrate) susceptible to electrostatic decay afterelectrostatic charging was first subjected to the bonding step. However,no product was determined to be defective in the inspection step inExamples 1 to 4 where the TFT substrate (first substrate) lesssusceptible to electrostatic decay after electrostatic charging wasfirst subjected to the bonding step. In comparative example 5, it wasable to prevent the product rejection, but the productivity wassignificantly reduced, because the first polarizing plate bonding stepand the inspection step were separated from each other and a long timefor waiting for the inspection was provided.

What is claimed is:
 1. A method for continuously manufacturing a liquidcrystal display panel, comprising: (a) feeding a liquid crystal cell ina continuous feed line, the liquid crystal cell comprising first andsecond substrates having different relative susceptibility toelectrostatic decay from each other, the first substrate beingrelatively less susceptible to electrostatic decay and the secondsubstrate being relatively more susceptible to electrostatic decay; (b)laminating a first polarizing plate to the first substrate of the liquidcrystal cell with a first laminating member adapted to press the firstpolarizing plate to the first substrate in a manner that a directcontact between the first laminating member and the first substrate canbe avoided, the first polarizing plate being provided from a firstpolarizing plate roll; then (c) laminating a second polarizing plate tothe second substrate of the liquid crystal cell with the first substratebeing in contact with a second laminating member through the firstpolarizing plate laminated to the first substrate in the step (b) sothat a direct contact between the second laminating member and the firstsubstrate can be avoided, the second polarizing plate being laminated tothe second substrate of the liquid crystal cell with a third laminatingmember adapted to press the second polarizing plate to the secondsubstrate, the second laminating member being provided opposite to andin cooperative relation with the third laminating member, the secondpolarizing plate being provided from a second polarizing plate roll,thereby obtaining a liquid crystal display panel, and (d) conducting aninspection of the liquid crystal display panel without applying voltageto the liquid crystal display panel, wherein the steps (a), (b), (c) and(d) are performed in a single continuous feed line for feeding theliquid crystal cell and the liquid crystal display panel.
 2. The methodaccording to claim 1, wherein the step (d) is performed at a positionwhere electrostatic has discharged sufficiently for the inspection fromthe first and second substrates in the continuous feed line.
 3. Themethod according to claim 1, wherein the first substrate and the secondsubstrate are determined based on the relative susceptibility toelectrostatic decay of each of the substrates, the first substrate beingrelatively less susceptible to electrostatic decay and the secondsubstrate being relatively more susceptible to electrostatic decay. 4.The method according to claim 1, wherein the step (b) comprises bondingthe first polarizing plate to the first substrate of the liquid crystalcell while feeding the liquid crystal cell from a feed-in side to afeed-out side along the feed line, and the step (c) comprises bondingthe second polarizing plate to the second substrate of the liquidcrystal cell while feeding the liquid crystal cell from a feed-in sideto a feed-out side along the feed line.
 5. The method according to claim1, wherein the step (d) comprises inspecting, in a line mode, the liquidcrystal display panel formed by the step (b) and the step (c), whilefeeding the liquid crystal display panel from the feed-in side to thefeed-out side along the feed line.
 6. The method according to claim 1,wherein the step (d) comprises: irradiating light to one side of theliquid crystal display panel and receiving, at another side of theliquid crystal display panel, the light transmitted through the liquidcrystal display panel to be inspected.
 7. The method according to claim1, wherein the first polarizing plate laminating step comprisescatching, between a pair of first bonding rollers, the liquid crystalcell and the first polarizing plate to bond the first polarizing plateto the first substrate of the liquid crystal cell, and the secondpolarizing plate laminating step comprises catching, between a pair ofsecond rollers, the liquid crystal cell with the first polarizing platebonded thereto and the second polarizing plate to bond the secondpolarizing plate to the second substrate of the liquid crystal cell. 8.The method according to claim 1, wherein the first polarizing plate hasan electrically-conductive layer.
 9. The method according to claim 8,wherein the electrically-conductive layer has a surface resistance of1.0×1012 Ω/square or less.
 10. The method according to claim 1, whereinthe second polarizing plate has an electrically-conductive layer. 11.The method according to claim 10, wherein the electrically-conductivelayer has a surface resistance of 1.0×1012 Ω/square or less.
 12. Themethod according to claim 1, wherein the step (b) includes laminatingthe first polarizing plate to the first substrate without contactbetween the first substrate and any bonding roller, thereby inhibitingthe first substrate from being electrostatically charged.
 13. A methodfor continuously manufacturing a liquid crystal display panel,comprising: (a) feeding a liquid crystal cell in a continuous feed line,the liquid crystal cell comprising first and second substrates havingdifferent relative susceptibility to electrostatic decay from eachother; (b) laminating a first polarizing plate to the first substrate ofthe liquid crystal cell with a first laminating member adapted to pressthe first polarizing plate to the first substrate in a manner that adirect contact between the first laminating member and the firstsubstrate can be avoided, the first polarizing plate being provided froma first polarizing plate roll; and then (c) laminating a secondpolarizing plate to the second substrate of the liquid crystal cell withthe first substrate being in contact with a second laminating memberthrough the first polarizing plate laminated to the first substrate inthe step (b) so that a direct contact between the second laminatingmember and the first substrate can be avoided, the second polarizingplate being laminated to the second substrate of the liquid crystal cellwith a third laminating member adapted to press the second polarizingplate to the second substrate, the second laminating member beingprovided opposite to and in cooperative relation with the thirdlaminating member, the second polarizing plate being provided from asecond polarizing plate roll, thereby obtaining a liquid crystal displaypanel, and (d) conducting an inspection of the liquid crystal displaypanel without applying voltage to the liquid crystal panel, wherein thefirst substrate and the second substrate are determined based on therelative susceptibility to electrostatic decay of each of thesubstrates.
 14. The method according to claim 1, wherein the step (d) isperformed at a position where electrostatic has discharged sufficientlyfor the inspection from the first and second substrates in thecontinuous feed line.